599 research outputs found
Beam Management for Millimeter Wave Beamspace MU-MIMO Systems
Millimeter wave (mmWave) communication has attracted increasing attention as
a promising technology for 5G networks. One of the key architectural features
of mmWave is the use of massive antenna arrays at both the transmitter and the
receiver sides. Therefore, by employing directional beamforming (BF), both
mmWave base stations (MBSs) and mmWave users (MUEs) are capable of supporting
multi-beam simultaneous transmissions. However, most researches have only
considered a single beam, which means that they do not make full potential of
mmWave. In this context, in order to improve the performance of short-range
indoor mmWave networks with multiple reflections, we investigate the challenges
and potential solutions of downlink multi-user multi-beam transmission, which
can be described as a high-dimensional (i.e., beamspace) multi-user
multiple-input multiple-output (MU-MIMO) technique, including multi-user BF
training, simultaneous users' grouping, and multi-user multibeam power
allocation. Furthermore, we present the theoretical and numerical results to
demonstrate that beamspace MU-MIMO compared with single beam transmission can
largely improve the rate performance of mmWave systems.Comment: The sixth IEEE/CIC International Conference on Communications in
China (ICCC2017
Context Information Based Initial Cell Search for Millimeter Wave 5G Cellular Networks
Millimeter wave (mmWave) communication is envisioned as a cornerstone to
fulfill the data rate requirements for fifth generation (5G) cellular networks.
In mmWave communication, beamforming is considered as a key technology to
combat the high path-loss, and unlike in conventional microwave communication,
beamforming may be necessary even during initial access/cell search. Among the
proposed beamforming schemes for initial cell search, analog beamforming is a
power efficient approach but suffers from its inherent search delay during
initial access. In this work, we argue that analog beamforming can still be a
viable choice when context information about mmWave base stations (BS) is
available at the mobile station (MS). We then study how the performance of
analog beamforming degrades in case of angular errors in the available context
information. Finally, we present an analog beamforming receiver architecture
that uses multiple arrays of Phase Shifters and a single RF chain to combat the
effect of angular errors, showing that it can achieve the same performance as
hybrid beamforming
Small Footprint Multilayered Millimeter-Wave Antennas and Feeding Networks for Multi-Dimensional Scanning and High-Density Integrated Systems
This paper overviews the state-of-the-art of substrate integrated waveguide (SIW) techniques in the design and realization of innovative low-cost, low-profile and low-loss (L3) millimeter-wave antenna elements, feeding networks and arrays for various wireless applications. Novel classes of multilayered antenna structures and systems are proposed and studied to exploit the vertical dimension of planar structures to overcome certain limita-tions in standard two-dimensional (2-D) topologies. The developed structures are based on two techniques, namely multi-layer stacked structures and E-plane corners. Differ-ent E-plane structures realised with SIW waveguide are presented, thereby demonstrating the potential of the proposed techniques as in multi-polarization antenna feeding. An array of 128 elements shows low SLL and height gain with just 200g of the total weight. Two versions of 2-D scanning multi-beam are presented, which effectively combine frequency scanning with beam forming networks. Adding the benefits of wide band performance to the multilayer structure, two bi-layer structures are investigated. Different stacked antennas and arrays are demonstrated to optimise the targeted antenna performances in the smallest footprint possible. These structures meet the requirement for developing inexpensive compact millimeter-wave antennas and antenna systems. Different structures and architectures are theoretically and experimentally studied and discussed for specific space- and ground-based appli-cations. Practical issues such as high-density integration and high-volume manufacturability are also addressed
Cavity-Backed Angled-Dipole Antennas for Millimeter-Wave Wireless Applications
A cavity-backed angled-dipole antenna is proposed for millimeter-wave wireless applications. The angled-dipole radiator is built on both sides of an RT/Duroid 5880 substrate (Δr=2.2) and fed by a parallel-plate transmission line. The cavity-backed reflector is utilized to improve the radiation characteristics of the angled dipole, such as gain, back-radiation, symmetric pattern, and similar 3âdB beamwidth in the E- and H-planes. The design, with a cavity aperture of 0.5λ28-GHzĂ0.5λ28-GHz, results in a S11<-10âdB bandwidth of 26.7â30.6âGHz, a gain of 6.6â8.0âdB, and a similar 3âdB beamwidth of approximately 70° for both the E- and H-planes. Eight-element linear arrays with the proposed antenna having a center-to-center spacing of 5.6âmm (0.52λ28-GHz) are characterized, fabricated, and measured. By applying nonuniform power distribution across excitations, the array achieves a scan angle up to 40° and a sidelobe level below â15âdB
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